1. Field of the Invention
This invention relates to a method for sealing a capsule by forming a band seal between a cap and a body of a capsule filled with drugs. More particularly, it relates to a method for forming a band seal between a cap and a body of a capsule in such a manner as to protect the band seal against defects such as bubbles and voids.
2. Prior Art
Capsules filled with various drugs are generally sealed in the prior art by fitting the cap on the body filled with drugs, and forming a circumferentially extending band seal axially spanning from the cap edge to the body surface to secure the cap to the body. The band sealing of capsules was originally employed for preventing mischief. Since it became a common practice to fill capsules with liquid drugs, the purpose of band sealing was diversified into, for example, purposes of preventing liquid leakage and preventing permeation of oxygen and water. It is thus desired to form a positive and accurate band seal on capsules.
In band sealing of capsules, however, bubbles and voids often occur in the band seal. Then, after band seals are formed, all the capsules must be inspected to pick up those capsules having defects in the band seal. Because the rejected capsules are discarded, a large number of defective band seals increases waste and is economically disadvantageous.
There is a need for a method for forming a band seal on a capsule while preventing bubbles and defects from occurring in the band seal.